What causes Ottawa grout to crack along the edges?

Grout cracking along the edges of tiles — particularly where tile meets a wall, cabinet, or another surface — is one of the most common tile complaints, and it's almost never the grout's fault.

The root cause is movement, not material failure. Grout is rigid and brittle. When two different surfaces meet — tile floor and drywall, tile and a cabinet toe kick, tile and a bathtub — they expand and contract at different rates with Ottawa's dramatic temperature and humidity swings. Rigid grout simply can't flex with that movement, so it cracks at the joint.

Perimeter joints and change-of-plane joints should never be grouted in the first place. The tile industry standard (TCNA guidelines) calls for these locations to be filled with sanded caulk that matches the grout colour, not grout itself. Caulk is flexible and can absorb the seasonal movement that Ottawa homes experience — from dry -30°C winters to humid 30°C summers, your house is constantly shifting slightly.

Subfloor deflection is the other major culprit. If the subfloor has any flex or bounce to it, grout joints throughout the field (not just edges) will eventually crack. A properly stiff subfloor — typically requiring a deflection of no more than L/360 — is essential before any tile is set. The contractors we match you with will assess subfloor rigidity before starting work, because no grout or adhesive can compensate for a bouncy floor.

In Ottawa specifically, homes with basements and crawl spaces see significant seasonal moisture movement in their framing, which accelerates this problem. Homes built on slab are somewhat more stable, but thermal movement still applies.

The fix is straightforward: rake out the cracked grout along the edges, clean the joint thoroughly, and fill it with a colour-matched sanded acrylic caulk. For field cracks caused by subfloor movement, the subfloor issue needs to be addressed first — otherwise new grout will crack again within a season or two.

If you're seeing widespread cracking across the field of the tile rather than just at edges, that's a more serious sign of subfloor problems worth having a professional assess. For a free estimate or a second opinion on a tile repair or reinstallation project, you can submit your details through Ottawa Floor Install and get matched with experienced local tile installers.